外拘束对焊接变形的影响较大，是影响焊接变形的重要因素之一. 相比于传统的刚性拘束，动态拘束能够实时的反映外拘束力在焊接过程中的变化效果. 在两条焊缝多层多道交叉焊的情况下，建立多场耦合分析模型，利用弹簧单元模拟较低刚度夹具的变形所带来的动态拘束力效果，考虑了变形量对于拘束力的反馈. 从拘束刚度、拘束距离、初始拘束力以及拘束宽度4个因素来探讨焊件的变形情况，得出各因素下的变形规律，并利用回归分析对4个因素进行综合评价. 结果表明，4个拘束因素的增加都能不同程度的减小变形量，拘束刚度、拘束初始力、拘束宽度的影响趋势较为相似，且拘束初始力影响最大，拘束距离在其范围内影响趋势为线性，且影响性最小.
External constraint has a great influence on welding deformation and is one of the important factors affected on welding deformation. Compared with the traditional rigid constraint, dynamic constraint can reflect the effect of external constraint force in the welding process in real time. In the case of multi-layer and multi-pass cross welding of two welds, a multi-body coupling analysis model was established, and the dynamic constraint force effect caused by the deformation of the low-stiffness fixture due to the deformation of the welds was simulated by using the spring element and considering the feedback of the deformation to the constraint force. The deformation of welded parts were discussed from four factors: constraint stiffness, constraint distance, initial constraint force and constraint width. The results showed that the amount of deformation reduced at different degrees with the values of four restraint variable increasing. The influence trends of the constraint stiffness, the initial constraint force and the constraint width were similar, and the initial constraint force was the most important influence factor. The influence of the restraint distance was minimal and its trend was linear.
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